【新手上路】cocos creator 示例游戏报错，跪求大神指点！！！

Creator 2.x
#1

文档示例学习过程遇到的报错：


示例游戏在PC环境运行正常，鼠标左键单机游戏画布控制台报错，如下： 
CCPhysicsManager.js:219 Uncaught TypeError: Cannot read property 'init' of undefined
    at CCClass.testPoint (CCPhysicsManager.js:219)
    at cc_MouseJoint.onTouchBegan (CCMouseJoint.js:229)
    at EventListeners.112.EventListeners.invoke (event-listeners.js:48)
    at _doDispatchEvent (event-target.js:70)
    at cc_Node.113.proto.dispatchEvent (event-target.js:403)
    at TheClass._touchStartHandler [as onTouchBegan] (CCNode.js:159)
    at _onTouchEventCallback (CCEventManager.js:493)
    at Object._dispatchEventToListeners (CCEventManager.js:628)
    at Object._dispatchTouchEvent (CCEventManager.js:550)
    at Object.dispatchEvent (CCEventManager.js:1057)

请教这是什么问题引起的？？？

#2

少了一句 。 cc.director.getPhysicsManager().enabled = true;